and I tried to recreate it for ubuntu 12.04 since a lot of things have changed.

Don't be scared with the length of this thread. It is really only the first two pages of the tutorial in a nutshell. It is the procedure I followed while I was trying to create a raid-1 on a running system that now has two identical disk drives.

Please try to follow it to see what is wrong because the tutorial of raid-1 for ubuntu 12.04 would be very useful and now is missing!

This is the procedure (not working yet):

Code:

just to see which disks are detected
cat /proc/diskstats
or
sudo lshw -c storage -c disk
Typically is sdb
Format your drive using the disk utility
In Disk Utily use default Master Boot Record
Take all the partition configuration from sda and put it in sdb. We want an exact copy so this is the first step
sudo sfdisk -d /dev/sda | sfdisk --force /dev/sdb
To format the drive
sudo fdisk /dev/sdb
for all partitions (sdb1 and sdb5) do the following:
Type 't' to change the partition's system id
Choose partition number
Type 'L' to list all codes
choose the code "fd" for Linux raid auto
finally on the main menu type 'w' to write (save) all the changes and quit
install mdadm
sudo apt-get install mdadm
To make sure that there are no remains from previous RAID installations on /dev/sdb, we run the following commands:
sudo mdadm --zero-superblock /dev/sdb1
sudo mdadm --zero-superblock /dev/sdb5
create raid-array
//sudo mdadm --create --verbose --auto=yes /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb
sudo mdadm --create /dev/md0 --level=1 --raid-disks=2 missing /dev/sdb1
sudo mdadm --create /dev/md1 --level=1 --raid-disks=2 missing /dev/sdb5
to verify execute this:
cat /proc/mdstat
should now show that you have two degraded RAID arrays ([_U] or [U_] means that an array is degraded while [UU] means that the array is ok)
Create filesystems on raid arrays
//sudo mkfs.ext4 /dev/md0
sudo mkfs.ext2 /dev/md0
sudo mkswap /dev/md1
Set new mdadm configuration by first backing up the original
sudo cp /etc/mdadm/mdadm.conf /etc/mdadm/mdadm.conf_orig
execute the line below to save to a temporary file
sudo mdadm --examine --scan > temporary.txt
copy and paste at the end(append) of this file:
sudo nano /etc/mdadm/mdadm.conf
or
sudo gedit /etc/mdadm/mdadm.conf
and of course delete temporary file
sudo rm temporary.txt
Next we modify /etc/fstab. Comment out the current /, /boot, and swap partitions and
add new lines for them where you replace the UUIDs with /dev/md0 (for the / partition) and /dev/md5 (for the swap partition), AGAIN don't know for third one
sudo nano /etc/fstab
or
sudo gedit /etc/fstab
Next replace /dev/sda1 with /dev/md0 in /etc/mtab:
sudo nano /etc/mtab
or
sudo gedit /etc/mtab
Now up to the GRUB2 boot loader. Create the file /etc/grub.d/09_swraid1_setup as follows
sudo cp /etc/grub.d/40_custom /etc/grub.d/09_swraid1_setup
sudo nano /etc/grub.d/09_swraid1_setup
or
sudo gedit /etc/grub.d/09_swraid1_setup
Copy paste this inside:
menuentry 'Ubuntu, with Linux 3.2' --class ubuntu --class gnu-linux --class gnu --class os {
insmod raid
insmod mdraid
insmod part_msdos
insmod ext2
set root='(md/0)'
echo 'Loading Linux 3.2.0-34-generic ...'
linux /vmlinuz-3.2.0-34-generic root=/dev/md0 ro quiet
echo 'Loading initial ramdisk ...'
initrd /initrd.img-3.2.0-34-generic
}
Make sure you use the correct kernel version in the menuentry stanza (in the linux and initrd lines). You can find it out by running
uname -r
Because we don't use UUIDs for our block devices, open /etc/default/grub...
sudo nano /etc/default/grub
or
sudo gedit /etc/default/grub
...and uncomment the line GRUB_DISABLE_LINUX_UUID=true
set BOOT_DEGRADED to true so that the system can boot from a degraded array without asking
sudo nano /etc/initramfs-tools/conf.d/mdadm
or
sudo gedit /etc/initramfs-tools/conf.d/mdadm
Now run
sudo update-grub
Next we adjust our ramdisk to the new situation:
sudo update-initramfs -u
Now let's mount /dev/md0 (we don't need to mount the swap array /dev/md5):
sudo mkdir /mnt/md0
sudo mount /dev/md0 /mnt/md0
Next we change the partition type of /dev/sda5 to Linux raid autodetect and add /dev/sda5 to the /dev/md1 array:
sudo fdisk /dev/sda
SUGGESTION HERE IS TO CREATE A Linux raid autodetect ONLY FOR THE SWAP PARTITION! Does this makes sense or should we do it for the main partition as well??
But even if we try the first attemtp to add the device to the array:
sudo mdadm --add /dev/md1 /dev/sda5
does NOT succeeed !
Now we copy the contents of /dev/sda1 to /dev/md0
Attempt to Copy 1:
cd /boot
sudo cp -dpRx . /mnt/md0
Attempt to Copy 2:
sudo cp -dpRx / /mnt/md0
You should now the md0 array in the output of:
mount
Afterwards we must make sure that the GRUB2 bootloader is installed on both hard drives, /dev/sda and /dev/sdb:
sudo grub-install /dev/sda
sudo grub-install /dev/sdb
reboot